1. Field
The present invention relates to swing working vehicles of a type having an extremely small swing radius at the rear and a type having an extremely small swing radius, and more particularly to a rotation table frame that is rotatably supported on a traveling device and attached with a working machine.
2. Background Art
Conventionally, in a swing working vehicle such as a power shovel, a rotation table frame is generally arranged on a traveling device; a working machine with attachments such as a boom, arm, and bucket is attached to a front portion of the rotation table frame; and an engine, counterweight, and the like are arranged on a rear portion of the rotation table frame. Also, the swing working vehicle is configured, based on a shape of the rotation table frame, as a type having an extremely small swing radius at the rear or a type having an extremely small swing radius, in which a swing radius is minimized.
The swing working vehicle of the type having an extremely small swing radius at the rear is configured such that a rear shape of the rotation table frame or the like is formed in an arc shape at an equal distance from a swing center, and a length twice as long as the swing radius of the rear end of the machine body is less than or equal to 120% of a vehicle width. In such a swing working vehicle, a front end of the machine body may project forward as compared with a swing radius of the rear end (see, for example, Patent document 1). On the other hand, the swing working vehicle of the type having an extremely small swing radius is configured such that a planar shape of the rotation table frame is close to a substantially circular shape, and an outermost swing radius of the machine body is equal to or less than a vehicle width (see, for example, Patent document 2). Also, some of the swing working vehicles of the type having an extremely small swing radius are configured such that a base portion of the working machine can be rotationally moved right and left (see, for example, Patent document 3).
In a conventional swing working vehicle as described above, a shape of the rotation table frame is different between the types having an extremely small swing radius at the rear and an extremely small swing radius, so that it has been necessary to manufacture the rotation table frame portion separately, which has been a factor that prevents an improvement in productivity and reduction in cost.                Patent document 1: Japanese Unexamined Patent Publication No. 1999-269926        Patent document 2: Japanese Unexamined Patent Publication No. 1999-343636        Patent document 3: Japanese Unexamined Patent Publication No. 2001-254397        